| With the rapid development of more powerful and intelligent mobile devices and high speed mobile communication technologies, ad-hoc networking systems have become a viable and promising means of achieving seamless and ubiquitous information sharing. In an ad-hoc environment, ensuring reliability of obtained information is a major problem owing to frequent partitioning of the network. In this context, replication provides a feasible method of improving data accessibility and decreasing access delay for mobile devices. However, the inherent characteristics of ad-hoc networks, including the lack of a predefined infrastructure, the relatively low bandwidth of wireless connections and the limited energy supply, make it difficult to directly apply conventional wired-network replication systems in mobile environments.; In this thesis, we propose a novel data replication scheme, called Distributed Hash Table Replication (DHTR), for achieving efficient data access and replica consistency maintenance in mobile ad-hoc networks. DHTR is based on an optimistic replication strategy that organizes all nodes into non-overlapping clusters. Cluster heads are responsible for maintaining replica directory information and relaying query and update messages from clients and replica managers. Distributed hash tables are used to facilitate the lookup of required directory information. We simulate the performance of DHTR and compare it with ROAM [28], another similar cluster-based replication solution, which verifies the effectiveness of our scheme. |
